Attrition-type flour mill with centrifugally controlled feeding means



ATTRITION-TYPE FLOUR MILLS WITH CENTRIF'UGALLY CONTROLLED FEEDING MEANS 2 Sl-lEETS-SHEET 1 Filed June 29. 1949 I INVENTOR 252., RNEY OYAL.

2 'r'ro Feb. 3, 1953 R. LEE

ATTRITION-TYPE FLOUR MILLS WITH CENTRIFUGALLY CONTROLLED FEEDING MEANS 2 SHEETS -SHEET 2 Filed June 29, 1949 INVENTOR ROYAL LEE flz ft 047/44 ATTORNEY Patented Feb. 3, 1953 UNITED STATES PATENT OFFICE ATTRITION=TYPE FLOUR MI'LL WITH CENTRIFUGALLY CONTROLLED FEED- ING MEANS Royal Lee, Elm Grove Wisi, assignor to Lee Foundation for Nutritional Research, Milwaukee, Wis., a corporation of Wisconsin Application June 29, 1949, Serial No. 101,957

, j 4 Claims. (01. 241-35) The present invention relates to grinding or grain flour and otherpulverizedu material.

An object, of the invention is to provide an i improved, grinding, or, attrition mill which. is of simple, durable andinexpensive construction, which issafe and economical in operation, which requires no skill ortraining to operate, and which is, well adapted for household use to grind whole grain flour in small quantities as needed.

. ing ahorizontal axis and provided at its. bottom it .pulverizing mills, and morev particularly to those i of the attrition type adapted for producing whole Another object is to provide a grinding mill O ..having improved automatic feeding means to avoid overloading or clogging of the mill and to permit grinding of material to a substantially uniform particle size.

A further object is to provide a grinding mill .havinga stationary. abrasive member or stone against. which the grain or other granular material tobe groundis spun or whirled at high-speed .bycentrifugal action to effect rapid attrition of i the material with a light touch.

The invention further consists. in the several features hereinafter described and claimed.

. In the accompanying drawings,

. Fig. 1 is. a; side, elevation of the portable flour mill constructed in accordance with the invention;

Fig. 2 is a fragmentary vertical sectional view of the mill;

Fig. 3 is a fragmentary side view of the mill,

. parts of a, fancasing. being shown insection;

. Fig. 4. is an elevation of the, feeding end of the mill, parts being :broken away and partsbeing shown in section;

i Fig. 5 is a fragmentary bottom view of the mill,

., partsbeingbroken away and partsbeing shown section;

Fig. 6 is. anenlarged detail sectional view of the peripheral, portion of the grinding chamber of the mill;

Fig. '7 is an enlarged detail sectional view taken on the line 1,'! of Fig. 4;

Fig. 8; isa fragmentary edge View of the rotor or, the mill;

Fig. 9- is, a detail view of a rotor hub, parts being shown in section, and

Fig, 1.0 is a detail end viewof themotor fan casing.

In the drawings, the numeral designates a base. memberof. the-tripod type having rubber feet l6, and a central; socket l1... A vertical tubular standard member lfl is detachably secured in the socket H, as by a screw l9.

with a tubular boss or. socket .21 in which the upper end ,of the standard, member is, detachably ecured. as by a. screw 22. Ahandle 2 3, is secured to the top wallQf, the fancasing, as by screws 24.

The motor fan casing has an inletend provided with a disk-shaped screen held in. place as by a snap ring 26, Fig, 3, and the other endof the casing is formed with interior radial ribs 21. and 21. projecting from the casingin an axial direction. The rib 21', which is wider than the other ribs, is at the bottom of the casing and is. provided witha radial set-screw 28.

An electric. motor 29 extends coaxially into the fan casing and includesa statoror field member 30 and a rotor .or armature 3i witha suitably journalled horizontal shaft 32, one end. of the shaft caryinga bowl-shaped fan 33 near the. inlet end of the casing. The motor further includes a, housing comprising rigidly, connected housing members 34 and 35 with cylindrical portions fitting, snugly against the inner edges of the ribs 21 and 21'. The millhousing member 3 5 has its cylindrical portion 36 secured in place by the setscrew 28,, and this housing member has a vertical wall 31. aaginst which, the ends of the ribs 21 abut. The ribbed fan casing and motor housing form cooling air passages 38 which have, outlets at the projecting ends of the ribs. The shaft 32 .is journalled in the motor housing, the bearing ,means including a ball bearing39 carried in a hollow boss 40 formed on the, housing wall 31.

The housing member 35 has anenlarged outer end portion with a marginal flange 4| which is secured, as by screws 42, to one side of a, ring The standard member supports thereon a-cupshaped frame-forming motor fan-casingI-i) havmember 43 the housing memberand ring member forming parts of a stator casing of the mill.

The ring member 43 is shrunk onto an annular abrasive stone 44 having a cylindrical inner periphery. The stator casing further includes a cover member 45 which is secured, as by screws provided-in its side; walls with small vent openings 59; which permit inflow of air. A metalring plate 55, such as of stainless steel, is. clamped between the stone 44- andthe flange All of the housing member 35; and is fitted in'a shallow rigidly secured to the disk, as by rivets 19.

recess 55 formed in this flange. The flat annular plate 55 has a central circular opening 51 which is slightly smaller in diameter than the inner diameter of the stone. As seen in Fig. 6, the opening 51 is beveled and flares toward the housing member 35. The bottom edge portion of the plate 55 is clamped to the ring member 53 by sheet metal clips 58 secured in place by screws 59. The abutting lower portions of the housing member 35 and ring member 53 project downwardly to form a discharge spout or nozzle 60 of oval or elongated shape, Figs. 4 and 5, and are secured together by screws 5|. A bead or flange 62 is formed around the lower edge of the dis charge spout for detachably holding the upper edge of a bag 63, the bag having an elastic re taining band 64.

A flat rotor disk 65 is carried by the motor shaft 32 and rotates within the stationary ring plate 55, there being a narrow slit-like annular orifice 66 between the outer edge of the disk and the inner edge of the ring plate. The space within the annular abrasive stone 44 and between the rotor disk 65 and the plate 41 forms a grinding chamber 51, and the space between the rotor disk and the vertical wall 31 of the housing member 35 forms a discharge chamber 69 communieating with the discharge spout 65. A shouldered spacer collar 59 bears against a shoulder 19 on the motor shaft, and the rotor disk 55 is clamped between the collar and a tubular hub member H by means of a nut-forming extension member 12 screwed onto the end of the shaft. The hub member has parallel .iaws l3 engaging flats 14 on the shaft, and further has a hexagonal flange [5 bearing against the rotor disk.

A felt sealing washer 16 is interposed between the collar 69 and the boss 40 of the motor housing member 35.

The rotor disk 65 carries thereon at the grinding chamber side a diametrically extending sheet metal channel member I! of U-shaped cross-section with out-turned edge flanges T8 The rotor disk carries thereon at the discharge chamber side a pair of sheet-metal angle plates 85 forming fan vanes to prevent packing of flour in the discharge chamber, the angle plates being secured in place by some of the rivets 19. The base or web of the channel member 71 is parallel to the rotor disk, and the intermediate portion of the base or web is cut away to form an elongated aperture or opening 8! through which the motor shaft passes. The hexagonal flange 75 of the rotor hub H fits between the parallel side flanges of the channel member, these side walls being spaced at opposite sides of the rotor axis.

A sleeve 82 is slidable on the shaft extension member 72 and is pressed outwardly by a coiled spring 83 surrounding the shaft and interposed between the sleeve and. the flange 15 of the hub member H, the outer end travel of the slidable sleeve being limited by a conical shoulder 84 formed on the socket head 85 of the shaft extension member. A feed disk 85 and a bowed leaf spring 81 are clamped on the sleeve 82 by a washer 88 which is engaged by a reduced outwardly spun portion 89 of the sleeve. The feed disk has a conical peripheral portion adapted to cooperate with a beveled annular surface 50 surrounding the central opening 54 of the wear plate 41 to form an annular feed passage for the grain. The feed disk may closely approach the beveled surface 99 but does not touch it.

The leaf spring 81 projects in opposite directions from the shaft and carries at its outer ends respective pairs of U-shaped governor weights 5i of skeleton form which are disposed within the channel member. The governor weights are made of sheet metal and are placed against opposite faces of the spring, the yoke portions of each pair of weights being secured to the spring by rivets 92. The edges 93 of the legs of each assembled pair of governor weights are arcuate and are shaped to a diameter approximately equal to the track-forming spaces between the rotor disk and the base or web of the channel 'member so as to have a slidable fit in these spaces. The channel member forms a guide for the governor weights and also forms a fan or impeller. It is sometimes desirable to coat or plate the rotor surfaces, particularly the tip portions of the leading faces of the channel mem her, with a layer of resistant metal, such as chromium, so as to minimize wear. As seen in Fig. 6, the inner face of the rotor disk 65 is preferably offset inwardly from the plane of the inner face of the flat ring member 55.

The electric motor 29 is preferably of a high! speed series or universal type, the speed of which decreases with load. In some instances, however, other types of motors may be used. The

motor is connected to a flexible conductor cord 94 having a terminal plug 95, the cord passing through an opening 96 in the motor housing member 35.

When the motor is at rest, the spring-pressed governor sleeve 82 carrying the rotatable feed disk 86 abuts against the conical shoulder 84 on the head of the shaft extension member 12, and the feed disk is close to the beveled edge 90 sur rounding the central opening 54 of the wear plate 41. Grain placed in the hoppr 50 will thus be prevented from entering the grinding chamber.

In operation, the motor is energized and drives the rotor 55 at a high peripheral speed. By way of example, a rotor speed of 7000 to 8000 R. P. M. has been found suitable in a mill having a grinding stone with an inside diameter of five inches. After a predetermined speed is attained, the governor weights 9| are caused to ,move outwardly in their guide tracks by centrifugal force, the arcuate edges 93 of the weights sliding along the web of the channel member 11. In their outward travel, the spring-mounted governor weights retract the feed disk 86 a sufficient distance from the edge of the feed opening 54 to permit a limited quantity of grain to enter the grinding chamber. The grain in this chamber is caused to swirl, tumble, and bounce on and around the cylindrical inner surface of the stationary abrasive stone by the centrifugal fanning action of the rotor disk and its channel member 17, thus abrading the grain and reducing it to flour. The fanning action also draws air into the grinding chamber through the feed opening and forces air and flour out through the narrow annular discharge slit 66 and into the discharge chamber 68, the slit forming a sieve opening for the flour. The flour falls in the bag 63, the discharge of the flour being assisted by the fanning vanes 80. The bag is sufficiently porous to permit escape of air. As more grain enters the grinding chamber, the load on the motor increases and causes the motor to slow down, thus reducing the centrifugal force on the governor weights and decreasing the gap between the feed disk and the edge of the feed opening 54 to shut off the flow of grain to the grinding chamber. The conical shape of the stop shoulder 84 prevents grain kernels from being pinched between the slidable sleeve 82 and this shoulder, which would prevent the closing movement of the feed disk. As more flour is produced and discharged from the grinding chamber, the load on the motor is gradually reduced, causing the motor speed to increase slightly and opening the feed passage to admit a small amount of grain to the grinding chamber. In this manner, the quantity of grain in the grinding chamber is limited and remains substantial- 1y constant, and overloading and clogging of the mill are avoided. The grain is ground to substantially uniform particle size or mesh, eliminating the need for subsequent sifting or bolt ing. As the flour is discharged promptly from the grinding chamber, very little flour is present in this chamber, thus avoiding interference with the grinding operation and permitting rapid reduction of the grain to flour.

While the mill is particularly adapted for grinding grain it may also be used for grinding other granular material. In the case of a flour mill, the width of the discharge slit 66 is a few thousandths of an inch. The relative axial position of the rotor disk 65 with respect to the ring plate 55 is not critical, and may vary to some extent without substantially changing the width of the discharge slit.

What I claim as new and desire to secure by Letters Patent is:

1. In a grinding mill, a stator having a rigid inner abrasive surface of generally cylindrical shape and further having axially spaced walls, a rotor having a disk between said walls and forming with said stator a grinding chamber at one side and a discharge chamber at the other side, said rotor disk having a peripheral edge forming with an interior surface of said stator a slit-like annular discharge orifice for passage of pulverized material from the grinding chamber to the discharge chamber, said grinding chamber having an inlet for granular material to be ground, and said discharge chamber having an outlet for pulverized material, fanning means carried by said rotor disk at the grinding chamher side thereof for impelling the granular material around said abrasive surface to pulverize the material, and fanning means carried by said rotor disk at the discharge chamber side thereof, said discharge orifice being relatively narrow.

2. In a grinding mill, a stator having an annular circumferential portion of generally cylindrical shape with an inner abrasive surface and further having an end wall with a central feed opening for granular material to be ground, a rotor in said stator having a ,disk axially spaced from said end wall and forming with said stator a grinding chamber, said stator having therein a circular opening within which the periphery of said disk loosely fits to form an annular discharge orifice ior passage of pulverized material, fanning means in said grinding chamber carried by said rotor for impelling the granular material around said abrasive surface, a centrifugally controlled closure member for said feed opening carried by said rotor and axially movable to vary the feed of granular material into the grinding chamber, and spring means carried by said rotor for urging said closure member toward closed position.

3. In a grinding mill, a stator having an annular circumferential portion of generally cylindrical shape with an inner abrasive surface and further having an end wall with a feed opening for granular material to be ground, a rotor having a disk in said stator axially spaced from said end wall and forming with said stator a grinding chamber, the periphery of said disk forming with said stator an annular discharge orifice for passage of pulverized material, radially extending guide means carried on said rotor disk in said grinding chamber and forming fanning means for impelling the granular material around said abrasive surface, a closure member axially movable on said rotor and cooperating with said feed opening to vary the feed of granular material into the grinding chamber, and centrifugal actuating means for said closure member including centrifugally influenced members movably confined by said guide means.

4. In a grinding mill, a stator having an annular circumferential portion of generally cylindrical shape with an inner abrasive surface and further having an end wall with a feed opening for granular material to be ground, a rotor having a disk in said stator axially spaced from said stator end wall and forming with said stator a grinding chamber, the periphery of said disk forming with said stator an annular discharge orifice for passage of pulverized material, a channel member of U-shaped cross-section diametrically carried on said rotor disk in said grinding chamber and forming fanning means for impelling the granular material around said abrasive surface, said channel member having spaced side walls disposed at opposite sides of the rotor axis and further having a base connecting said side walls and spaced axially from said disk, said channel member base having an opening intersected by the axis of said rotor, a closure member axially movable on said rotor and cooperating with said feed opening to vary the feed of granular material into the grinding chamber, and centrifugal actuating means for said closure member passing through said opening in the base of said channel member and including centrifugally influenced members movably confined by the outer portions of said channel member.

ROYAL LEE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 341,439 Allen May 1'1, 1886 420,464 Perry Feb. 4, 1890 832,801 Milross Oct. 9, 1906 1,081,860 O'Neill Dec. 16, 1913 1,267,110 Parsons et al. May 21, 1918 1,352,189 Haeberlein Sept. '7, 1920 1,541,903 Crites June 16, 1925 1,628,295 Wickland May 10, 1927 1,697,704 Wood Jan. 1, 1929 2,100,200 Mosley Nov. 23, 1937 2,240,269 Sallee Apr. 29, 1941 2,361,278 Evans Oct. 24, 1944 2,392,331 Lykken Jan. 8, 1946 2,501,622 Smith Mar. 21, 1950 FOREIGN PATENTS Number Country Date 229 Great Britain Jan. 30, 1854 286,533 Italy Aug. '15, 1931 646,437 Germany June 16, 1937 

